Method and apparatus for forming composite metal articles



W. BROWN Jan. 11, 1944.

METH OD AND APPARATUS FOR FORMING COMPOSITE METAL ARTICLES Filed Jan. 21, 1941 FIG.I.

FIG.2.

INVENTOR.

WALTER BROWN ATTORNEYS Patented Jan. 11, 1 944 UNITED sTA'ras PATENT OFFICE &339.141

METEO!) AND APPARATUS FOR FORMNG COMPOSITE METAL ARTICLES Walter Brown, Her-masa Beach, Calif.

v Application January 21, 1941, Serial No. 375345 2 Claims. (Ci. 22-65) The invention relates to a method and apparatus for iorming composite metal articles of that type including a cylindrical sheu formed of one metal and a coating of another metal integrated therewith, which coating may be applied either inside, outside or both inside and outside of said shell. Heretofore structures of this type'have been formed by placing the coating metal within the shell or a cylindrical container for the shell, closing the ends of the container to seal the same with exception of a slight vent for escape of gases thereby maintaining a non-oxidizing atmosphere within the shell, then heating the container sufilciently to melt the coating metal and finally rotating the container to distribute the molten metal by centrifugal action continuing the rotation until such metal is solidifled.

There are several obiections to the process just described particularly where the coating metal has a relatively high melting point. First, there is danger of overheating the shell or container before the coating metal is fused and raised to the proper temperature tor welding to the shell. Second, there is a tendency for the molten metal to diifuse within itself a certain amount of metal derived from the heated shell in contact therewith and, therefore, it is highly desirable to limit the time interval in which the molten metal and hea'ted shell are in contact which is dimcult to accomplish where the coating metal is melted within the shell. Third, for certain struetures the coating metal may have a melting point which is nearly as high or even higher than the melting point of the metal forming the shell. This would render it impossible to melt the coating metal within the shell without destroying the latter. Fourth, even where 'the melting point of the coating metal is lower than that-oi the shell,- it may be dimcult to aceomplish the melting. This is particularly true where the coating isto be applled both inside and outside the shell which latter is positioned within an outer container. The space between the container and the shell. which is to receive the molten metal formin: the outer coating will form a heat insulation which retards penetration of heat from the outside into the interier.

It is the object of this invention to overcome the difhculties above reierred to and to this end the invention consists, first; in the method, and second, in the apparatus as hereinafter set forth.

In the drawing- Figur-e 1 is a vertical central section through one form of apparatus suitable for carrying out my improved method;

Figura 2 is a similar view through a portion of an apparatus of modified construction.

As shown in Figure 1, A is a cylindrical shell "which is to be coated with another metal, said shell being formed of -any suitable material, such as steel. B is a crucible of refractory material temporarily attached to one end of the shell in axial alignment therewith so as to project therebeyond. The attachment may be formed by an annular metallic member C which flts within the cylindrical shell and is secured thereto by welding as indicated at D. The crucible B is preferably of an upwardly aring form, its upper edge abutting against the member C and being held thereagainst by a surrounding metallic ring E welded to the member i C as indic'ated at F. This will hold the crucible and shell in coaxial alignment. There is also a head G secured to the opposite end of the shell by welding as at H. This head has a small vent aperture or port I therein to permit the escape of gases when the structure is heated.

In carrying out the process, the metal for forming the lining is placed in the crucible prior to the closing of the shell together with a small amount of volatile material, such as alcohol. which, when heated, will be vaporized driving out the air from the interier of the shell through the c vent port I. This will produce ,a' neutral atmosphere which will prevent oxidation of the metal while being melted as well as protecting the inner surface of the shell. The structure is then placed in an upright position within the fumace so that the crucible will be subiected to a higher degree of heat than the shell. This will guard against any overheating of the shell and will also raise the temperature of the molten metal to above the temperature of the shell which is desirable." After being fully heated. the structure is removed from the furnace and is placed in a,

spinning apparatus with the axis of rotation substantially horizontal. The molten metal will thus flow from the crucible into the shell and will be distributed by centrifugal action so as to form a lining of uniform thickness.

During the spinning operation, the shell is externally cooled so that the time interval in which the molten metal is in contact therewith is comparatively short. This will prevent any contamination of themolten metal due to absorption of metal from the shell.

My improved process may be used with various llning metals but it is particularly useful with metals oi' high meltingpoint. "I'hus, i! desired,` the lining metal may be a material'havlng a high er melting point than that of the metal i'o'ming the shell. The fact that the crucible projects downward beyond the end of the shell permits of arranging the same within the i'urnace in a zone of higher heat thereby avoiding overheating of the shell.

In Figure 2, I have illustrated a modified form of apparatus in which the shell A' is positioned however, necessary as the cont'ainer may be formed of a metal tube which can be easily machined away from the inner structure.

What I claim as my invention is:

1. In a process or forming composite metal structures, the steps of attaching a ref'actory cru- This is not,

cible to one of a cylindrical container to proiect therebeyond in a coaxial alignment therewith, placing a perforated tube to be coated lconcentrically within said container to leave an annular space therebetween, placlng a metal to be melted within the crucible, substantially closing the opposite end or the container to maintain therein b non-oxidizing atmosphere, simultaneously heating both container and crucible thereby melting the metal within the crucible, and in splnning the crucible and container about their common axls to discharge the molten metal from the cruclble into the container distributing it by centritugal action about the lnner surface of the tube and through the peroratlons filling the space surrounding the tube.

' 2. Anassembly for lining articles comprising a cylindrical metalllc shell, end pieces secured to each end of said cylindrical shell, one of said end pieces having a pouring opening therein. a crucible having an outwardly flaring outside wall and a conical ring attached to the end piece having the pouring opening and engaging the flaring wall of said cruclble to hold the letter in com munication with said cylindrical shell.

WALTER BROWN. 

